Biochemical reactions utilizing enzymes as a catalyst, such as (a) the hydrolysis of hydrophobic fats and oils, and (b) the esterification of hydrophobic higher fatty acids and hydrophilic polyhydric alcohols, have heretofore been performed by immobilizing the enzymes, or by dissolving or dispersing the enzymes in a hydrophilic substrate and completely mixing together the hydrophobic and hydrophilic substrates which are incompatible with each other.
In the latter process wherein the enzymes are not immobilized, the hydrophobic and hydrophilic substrates are converted into an emulsion when completely mixed together since the enzymes also act as surface active agents. When heated to temperatures of at least about 80.degree. C. after the reaction is completed, the emulsion separates into two layers. At such a temperature, the enzymes are inactivated, and the thus-inactivated enzymes enter the hydrophobic layer.
In the case of the above-described hydrolysis of fats and oils, even if the emulsion separates into two layers, part of the glycerol produced, which is a hydrolyzate, enters and mixes with the hydrophobic higher fatty acid layer. Similarly, in the case of the esterification of hydrophobic higher fatty acids and hydrophilic polyhydric alcohols, the product, i.e., a hydrophobic ester layer, is contaminated with part of the unreacted polyhydric alcohol. From an economic standpoint, the inactivation of expensive enzymes is a particular serious disadvantage of the mixing process.
In order to overcome the above-described problems of the latter process, the former process as described above, was developed, i.e., wherein immobilized enzymes are used and the enzymes can be recovered. However, this process has disadvantages in that the cost of immobilization is high and the enzyme activity is low. In addition, the heterogeneous reaction cannot be performed efficiently. Thus, the process utilizing immobilized enzymes has not been put into practical use.